You can download the book in PDF format.

Below is the Preface from the book.

Preface

These notes for a graduate course in set theory are on their way to becoming a book. They originated as handwritten notes in a course at the University of Toronto given by Prof. William Weiss. Cynthia Church produced the first electronic copy in December 2002. James Talmage Adams produced a major revision in February 2005. The manuscript has seen many changes since then, often due to generous comments by students, all of whom I here thank. Chapters 1 to 11 are now close to final form. Chapters 12 and 13 are quite readable, but should not be considered as a final draft. One more chapter will be added.